1. Field of the Invention
This invention relates to simulation modeling and analysis of power distribution in electrical systems and more particularly to a machine comprising one or more computing devices configured as a systems power distribution tool for use with event-driven systems that include a topology of power sources, resistive physical interconnects and event-driven fixed power loads.
2. Description of the Related Art
Electrical systems may be characterized as including a power source, electrical loads and a network of physical interconnects to distribute power from the source to the various loads. These systems may be static or single-event in which the load conditions are fixed throughout the timeline. More typically, the systems are dynamic including multiple events in which the load conditions change with time. Most of the loads are fixed-power loads in which the load power is fixed for a given event but may vary with the different events. Systems may also include fixed current or fixed resistance loads. The power source is typically either a fixed-voltage source or a depletion-voltage source (e.g. a battery). Some systems utilize a fixed-voltage source for a portion of the timeline and a battery for the remainder. These systems may range from designs of buildings, ships, aircraft, missiles, solar cars, cell phones etc.
In general, each load has a specified operating voltage and a margin that defines both under and over voltage conditions for the load. Above the over voltage threshold the load may be damaged. Below the under voltage threshold the load will not function properly. Each interconnect has a resistance and a current derating value above which the interconnect may be damaged (e.g. burn up). A power source is characterized by its source voltage and possibly its peak current, peak power or total current capabilities.
The system designers task is to design a power source and robust and preferably balanced interconnect topology that distributes power to the electrical loads subject to other constraints on the system. These constraints can range from very specific such as requiring the use of certain existing interconnects, specifying input and output impedance, peak power constraints etc. to more general such as reducing size, weight, total power and cost.
The standard design methodology is to select a source voltage and allocate a certain voltage drop for the physical interconnects to set the load voltages to “push” the current required to power the loads. The interconnect and load designers separately design to their specifications. Interconnect designers design the interconnects to satisfy the derating criterial based on the nominal load voltages and allocated drops. Their focus is to save weight and reduce cost. The load designers specify their worst case loads. The power source designers use these worst case loads to form the output power specification for the source.
When the power source, distribution network and loads are integrated a variety of problems are exposed. Often the interconnect topology is not robust, some of the interconnects will fail derating under actual operating conditions. The distribution network may not provide proper voltages to the loads causing both under and over voltage conditions. Over voltages may be addressed by adding a pre-compensator to the load but this expends resources. The power source is often over designed due to ‘margin stacking’ of the worst case loads. The process to redesign the separate components and reintegrate the system is time consuming and costly and often produces a sub-optimal or unbalanced system.